{ 7 × [ 5 × ( 7 - 2 x ) - 2 ] + 4 } : 5 - 4 = 1
{ 7 × [ 5 × ( 7 - 2 x ) - 2 ] + 4 } : 5 = 1 + 4
{ 7 × [ 5 × ( 7 - 2 x ) - 2 ] + 4 } : 5 = 5
7 × [ 5 × ( 7 - 2 x ) - 2 ] + 4 = 5 × 5
7 × [ 5 × ( 7 - 2 x ) - 2 ] + 4 = 25
7 × [ 5 × ( 7 - 2 x ) - 2 ] = 25 - 4
7 × [ 5 × ( 7 - 2 x ) - 2 ] = 21
5 × ( 7 - 2 x ) - 2 = 21 : 7
5 × ( 7 - 2 x ) - 2 = 3
5 × ( 7 - 2 x ) = 3 + 2
5 × ( 7 - 2 x ) = 5
7 - 2 x = 5 : 5
7 - 2 x = 1
2 x = 7 - 1
2 x = 6
x = 6 : 2
x = 3 → numarul aflat prin metoda mersului invers